The present invention relates to a control method for the conservation of energy in an industrial plant supplied by a utility company.
There are two competing economic interests in the user's plant regarding energy consumption. One is to meet the plant production requirements; the other is to limit billing from the power company. Billing extends for accounting purposes over a full month - the billing period. Control of the loads, to keep the amount of the KW-Hour within an assigned limit while exercising decisions to switch or not to switch specific loads into or out of production, is effected during shorter periods of 15 minutes - the demand period. Power demand control during the demand periods keeps the accumulated KWH within the prescribed limit, e.g., not to exceed an amount of available power acceptable at a given rate. Power demand control also insures within the demand limit the most effective utilization of the loads available or required during such period of control. Power demand control most efficiently uses the assist of a computer. In contrast to power demand control, computer techniques have evolved which aim at energy conservation. By energy conservation is meant reducing energy consumption so that over the billing periods the number of KWH billed will be minimized.
It is known from an article in "Computer World", Sept. 27, 1976, page 11, entitled, "Energy Conservation Seen As Major DP Application" to use computers in order to save energy for industrial and commercial applications. To this effect, it is suggested in this article to "optimize a facility's load profile", meaning by this to monitor and optimize with computers the scheduling of energy consumption within a facility. Under this concept, the load will be rescheduled at certain times of the day, week, or year which are more favorable from a point of view of energy production, in particular by avoiding the periods of peak consumption, e.g., of peak production of energy.
The present invention proposes to apply computer techniques for energy conservation with an entirely different concept. The high peak hours are not used as a basis to reschedule loads to low peak hours. Instead, within a plant energy consumption by the user is automatically reduced whenever this can be done without harm to the production.
The object of the present invention is to automatically reduce energy consumption in relation to the level of the demand of power within a plant facility.
Another object of the present invention is to reschedule the loads in a plant facility in accordance with a predetermined load pattern whenever the demand of power in the plant reaches a preestablished level.
A further object of the present invention is to control the demand of energy in a plant by establishing a load pattern in accordance with a priority schedule defining a required production level, and to abandon said priority schedule load control to control the consumption of energy in accordance with a second load pattern whenever the demand of energy falls below a predetermined level.
Still another object of the invention is to control energy consumption in a plant in accordance with the production activity in the plant by reference to the actual demand of power in the plant.
Further, an object of the present invention is to automatically change the priorities and modify the constraints of the loads in an industrial plant in relation to a change in the activity therein.
Finally, another object of the present invention is to relate changes in the acitivity of an industrial plant to human activity in the plant, and to establish standards of consumption of energy in the plant reflecting more closely such related changes.